And I'm David Greene. Two large objects showed up satellite images bobbing in a remote part of the Indian Ocean.

WERTHEIMER: Now the search is on to find those objects and see if they are part of the missing Malaysia Airlines plane. Search planes and boats are covering an area about 1,500 miles southwest of Perth, Australia.

GREENE: And NPR's David Schaper joins us on the line now with the latest on the search. David, good morning.

DAVID SCHAPER, BYLINE: Good morning, David.

GREENE: So what do we know as of now about what's playing out in that remote part of the Indian Ocean?

SCHAPER: Well, authorities in Australia say that so far the search planes have not been able to locate those two objects that had been spotted in the South Indian Ocean by satellite. There are concerns among some that the debris, if it even was from the plane, has sunk to the bottom of the ocean. You know, 24 to 36 hours ago, Australia's prime minister and others were calling this the strongest possible lead as to the whereabouts of the missing Malaysian airliner.

Now officials are saying that they still are optimistic and will continue to hunt for at least another day.

GREENE: And you know, when we first heard about objects being spotted on satellite, you had this feeling that you could really pinpoint something, but this still a huge area of ocean, thousands of square miles. It's a long distance from land. I mean how do these search crews figure out exactly where to look for these objects?

SCHAPER: Well, it is difficult. These satellite images now are five days old and there's no doubt that the objects have drifted quite a bit. So the first thing search crews did was they dropped these data buoys in the water in the area where the objects were at the time. They gathered data on the ocean currents and wind speeds and that will help them figure out about how far the material may have traveled and in which general direction it may have gone.

But you know, this is a part of the ocean that is notorious for bad weather, fierce winds. There's a lot of high wave action and strong currents, and I'm told that is complicating the search for where this debris may be.

GREENE: And David, we had heard that there planes heading there, boats. I mean, do you understand exactly how this search is taking place?

SCHAPER: As the experts in these sorts of search missions have told me, the search planes that are being used are high tech submarine hunters. Now, it takes a good three or four hours to get to the search area from the Australian coast, so the planes that they're using can only search for a couple of hours before they have to head back to land to refuel.

But the Australian planes, they're American-made P-3 Orions, and there's an American anti-sub aircraft, the Navy's P-8 Poseiden, and these are equipped with the latest search tools. They have very sophisticated radar. It's designed to locate something as small as a submarine's periscope sticking out the water. And they have something else that they can deploy if they think that they're close to where the plane went down.

It's called a sonobuoy, sonor-equipped buoys that can actually listen for the underwater locater beacons of the flight recorders. Here's Bill Waldock, director of the crash lab at Embry-Riddle Aeronautical University in Prescott, Arizona, to explain what that means.

BILL WALDOCK: What it's designed to do in sub hunting is it sends our a sonar signal so if you've got a submarine in the area , you lay a line of sonobuoys, and they help you pinpoint where the sub is.

SCHAPER: Now, Waldock says the searchers have to be pretty close to the wreckage to hear the plane's beacons with those sonobouys, assuming that the beacons are still transmitting, and that's why finding any debris from the plane on the surface of the water is so important.

GREENE: So David, you're describing a lot of high tech stuff. I mean are human beings also involved? I mean could this come down to a person just actually spotting one of these objects on the ocean?

SCHAPER: Well, absolutely, David. Experts say it is most likely that the radar would first locate the floating objects or the debris. And first of all, they're not going to have crew members looking out the windows with binoculars. They're going to use sophisticated what's called electro optical infrared imaging. It's similar to what military reconnaissance and strike drones use.

That will give them a very detailed video image of the object. But that still might not be enough to positively identify what the debris may be. And experts say it will ultimately come down to just getting some eyeballs on the debris, and that may mean getting a helicopter there or a boat there so you can put people in the water with the object.

GREENE: All right. NPR's David Schaper updating us on that search in the remote South Indian Ocean for debris that could, could be part of that Malaysian airliner. David, thanks very much.